Scanning electron microscopy of arteriovenous malformations.

Although arteriovenous malformations (AVMs) have been known to have direct communications between arteries and veins without interposing capillaries, the exact location of arterial and venous junctions have not been defined. Utilizing microscopic and endoscopic observations, Yamada and associates identified shunting arterioles (50 mu-250 mu) directly connected to the AVM core vessels. While dissecting the AVMs in functional areas of the brain, shunting arterioles were sectioned to interrupt the arterial blood supply. This technique allowed cleavage formation between the core vessels and surrounding brain, thus avoiding brain tissue removal and preserving microcirculation to functionally critical brain. We demonstrate histologically for the first time by scanning electron microscopy shunting arterioles and communicating venules (20 mu-200 mu).